1. Field of the Invention
The present invention relates generally to electronic devices and, more specifically, to processing of audio in an electronic device.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
The trend in consumer electronics is to combine multiple functionalities into a single portable electronic device. For example, cell phones and media players are no longer merely distinct devices, each with their own unique capabilities. Rather, cell phone and media player functionalities can now be merged into one multimedia device with a multitude of capabilities. Modern cell phone/media players are often packed with dozens of additional features which include: playing of audio and video, taking of still pictures, recording video, playing video games, GPS navigation, web surfing, downloading of streaming media from the Internet, Bluetooth and WiFi communications, emailing, text messaging, etc.
One advantage of combining all of these features into one device is that it eliminates the need to carry multiples devices. From an economic standpoint, combined devices also reduce overall cost to the consumer because the electronics that make up the device are used for multiple applications rather than having duplicate electronics with specialized functions. Additionally, by combining an array of electronics with a variety of capabilities it may be possible to provide cross-functionality, in which one device takes advantage of the capabilities of another device.
Typically, the added functionality of a multimedia device is controlled by a central processing unit (CPU) that has direct access to all of the features provided in the device. For example, in the case of processing stored music, a CPU may directly control the routing of data between various components such as memory, digital signal processors, decoders and media playing circuitry. In this type of design, most data, including copyright protected media such as music or music videos, will eventually pass through the CPU for processing and routing. The drawback of this type of design is that the CPU is continually powered up, active and consuming battery power.
Additionally, the telephone audio in a typical multimedia device may be processed by dedicated circuitry rather than the CPU. Generally, telephone audio uses dedicated circuitry to guarantee a hard upper bound on real-time delay, both to comply with the various regulations that bear upon telephones, and to avoid delays that degrade the user experience. This may mean that dedicated circuitry is used to process telephone audio so that telephone audio can bypass the CPU. The circuitry dedicated to the processing of telephone audio is typically very simple, limited to equalization and routing functions. The drawback of this approach is that simplicity of the telephone processing circuitry limits the type of electronic enhancements of telephone audio that might otherwise be possible.
Another drawback of combining multiple capabilities in one device is that as multimedia devices become more functional, the risk of unauthorized copying and distribution of copyright material becomes greater. For example, a multimedia device that is capable of downloading music and/or videos from the Internet can also potentially store the media onto internal memory or an external device and redistribute the media via email or other Internet communication medium as well as by hard copy. Encryption of copyrighted material may help to make such material less susceptible to illegal copying; however, in the typical multimedia device decrypted media may eventually become available to the CPU and, therefore, vulnerable to illegal copying and distribution.
Thus, typical multimedia or audio devices of the prior art include a CPU that is directly coupled to all of the audio components, including a digital signal processor (DSP) and peripheral input/output devices. In a typical prior art device, the CPU would be directly involved in many of the process steps for processing audio, including routing encoded or compressed data to a digital signal processor, receiving the uncompressed data from the DSP and routing the uncompressed audio to a peripheral device.
It may be advantageous, therefore, to provide a multimedia device with an audio subsystem that is not directly controlled by the CPU. It would also be advantageous to provide a device that processes a wide variety of media and takes advantage of the enhanced capabilities that a multimedia device can provide, but, at the same time, provides optimal performance of a dedicated device. For example, it may be advantageous to provide a multimedia device that combines the capabilities of an audio player and a cell phone, but also consumes very low power while operating as an audio player or a cell phone. Additionally, it may be advantageous to provide a multimedia device with enhanced copyright protection that prevents users from illegally distributing copyright protected material.